Preservation of rubber



Patented Apr. 20, 193'? PRESERVATION F RUBBER Ira Williams, Woodstown,and William A. Doug lass, Penns Grove,

N. J., and Arthur M. Neal,

Wilmington, Del., assignors to E. I. du Pont de' Nemours & Company,Wilmington, Del., a cor-- iteration of Delaware No Drawing. Originalapplication October 25,- 1932, Serial No. 639,478. Divided and this ap-;plication September 11, 1934, Serial No. 743,553

18 Claims.

This invention relates to the preservation of rubber and moreparticularly to the incorporation of compounds which retard thatdeterioration which is due to the action of heat and oxidation.

It is well known that many materials possess the property, whenincorporated in rubber, of retarding that deterioration which rubbernormally undergoes when exposed to the action of heat and oxidation.Among the earliest types of compounds employed for this purpose were thenaphthalene diamines suchas 1-8-naphthalene diamine, as disclosed in U.S. Patent 1,532,398. The importance of this class of compounds islessened, however, by the fact that they are relatively toxic and alsobecause of their activating efiect on many of the common acceleratorsused in practice.

An object of the present invention is to provide vulcanized rubberhaving improved age-resisting properties. A further object is toincorporate in rubber a new class of compounds having exceptionalpreserving properties which are non-toxic and in general have no effecton the rate of cure when incorporated into rubber prior tovulcanization. Other objects are to provide new compositions of matterand to advance the art. Still other objects will appear hereinafter.

These objects may be accomplished in accordance with our invention whichcomprises incorporating into rubber, before or after vulcanizationthereof, compounds of the type:

2:7-diphenyl naphthalene diamine 2 :7 -di-p-phenetyl naphthalene diamine 1 :5-diphenyl naphthalene diamine 118-(lipheny1 naphthalene diamineO- i-O 1-phenyl-4p(0H)-phenyl naphthalene (liamine It will be seen fromthis table that the com-' pounds of this class are very effective as in-1 :5-di-p (OH) -pl1enyl naphthalene diamine HN OH hibitors of thatdeterioration WhlCh rubber normally undergoes due to the action of heatand 5 oxidation.

Other compounds of this same type which may be mentioned are:

HO NH 1 :2-di-p-t0lyl naphthalene diamine 10 1:5-dibutyl naphthalenediamine H H N--C4Ho N 15 NOCH:

l HeC4-N-H In order to test this class of compounds the1:3-di-p-phenetyl naphthalene diamine 20 two following stocks wereprepared:

H A B NQoeim 25 gale crea III 1110 X1 H Titanox". 50.0 50.0 N O' Sulfurulfid Tetra methyl thiuram monos e 1:5-di-p(0H)phenylamido naphthalene1.0 1=6-d1buty1 naphthalene dlamme H 30 Titanox is the trade name of amixture of 75% barium sulfate and l 25% titanium dioxide. (GardnerChemical Synonyms and Trade -N- O4H samples in a Bierer Davis bomb at 70C. and 300 Names 3d Ed. 1930 p. 328.)

These stocks were cured to comparable states of cure at 20 lbs. steampressure. Their relative aging properties were determined by suspendingcintN 1:7-diphenyl naphthalene diamine lbs. oxygen pressure. After 7days under these conditions stock A was completely deteriorated, Hwhereas stock B, containing the deterioration in- H 1 hibitor, was stillin good condition after 17 days, 1 when the test was discontinued.

In order to test this class of compounds still further the followingstocks were prepared:

A B O D E F G H I Pale erene 100 100 100 100 100 100 Zinc mn'rin 100 100100 100 100 100 Lithopnne 20 20 20 20 20 20 Stearic acid 1 1 1 1 1 1Sulfur 3 3 3 3 3 3 Diortho tolyl guanidine 75 75 .75 75 75 752:7-diphenyl naphthalene diamine. 1 2 di-p-phenetyl naphthalene diamine1 diphenyl naphthalene diamin 1:8-diphenyl naphthalene diaminel-phenyli-p-phenetyl naphthalene diamine 1 l-pheny1-4-p(OH) phenylnaphthalene diamine I 1 1:5-di-p(0H) phenyl naphthalene diamine 1 1-dibutyl naphthalene dim-nin These stocks were vulcanized to acomparable state of cure at 40 lbs. steam pressure. Their agingproperties were determined by suspending them in an oxygen bomb at 70 C.and 300 lbs.

2 :3-di-p-anisy1 naphthalene diamine oxygen pressure for 48 hours. Theresults of this test are given in Table I. N-GOCH:

Table I 11 I N 0011. Original Tensile after 0 Stock tensile aging I,Completely 2:ii-d1ethyl naphthalene diamine A 3050 .deteriorated B 29752500 o 2015 2350 D 3150 2350 E 3025 ,2375 I F 2875 2525 G 2000 12500 H3100 2300 I 3225 2725 1-phenyl5-p-anisyl naphthalene diamine1-p-phenetyl-6-p-t0lyl naphthalene diamine ilgaw. re

2-in-tolyl-7-o-phenetyl naphthalene diamine TIJ CE GER- 2-propyl-6-ethylnaphthalene diamine CaH1 C zHaN 1-butyl-4-phenyl naphthalene diamineNC4H0 1-ethyl-3-p-tolyl naphthalene diamine 2-propyl-3-p-phenetylnaphthalene diamine i NOooiHi 1:5-dibenzyl naphthalene diamine l-p H)-phenyl-7-isopropyl naphthalene diamine H-ON 2-benzyl-6-p-(OH) phenylnaphthalene diamine 2b-pl1enyl-ethyl-7-ethyl naphthalene diamine Thecompounds of our invention are likewise effective when added to therubber after vulcanization by any of the commonly applied methods ofimpregnation.

In the examples we disclosed the use of one part of the deteriorationinhibitor to 100 parts of the rubber. However the proportion ofdeterioration inhibitor employed may be varied within rather widelimits, depending upon the desire of the user and the nature of therubber stock employed.

This is a division of our co-pending application Serial No. 639,478filed October 25, 1932.

While we have disclosed compositions containing specific compounds andspecific methods oi. preparing the same, it will be readily apparentthat the specific compounds employed and the methods of employing thesame may be widely varied without departing from the spirit of ourinvention. Accordingly, the scope of our invention is to be limitedsolely by the appended claims construed as broadly as is permissible inview of the prior art.

We claim:

1. The method of preserving rubber which comprises incorporating therein1-5-diphenyl naphthalene diamine.

2. Rubber having incorporated therein 1-5- diphenyl naphthalene diamine.

3. The method of preserving rubber which comprises incorporating thereina lzfi-naphthalene diamine in which each amino nitrogen carries onehydrogen atom and one hydrocarbon radical of the group consisting ofalkyl, phenalkyl and phenyl radicals.

4. The method of preserving rubber which comprises incorporating thereinan N,N di-substituted 1:5-naphthalene diamine in which each Nsubstituted group is a member of the group consisting of unsubstitutedand substituted alkyl, phenalkyl and phenyl groups in which substituentsare restricted to members of the group consisting of hydroxy, alkyl andalkoxy radicals on phenyl radicals.

5. The method of preserving rubber which comprises incorporating thereinan N,N' di-substituted 1:5-naphthalene diamine in which each Nsubstituted group is a member of the group consisting of unsubstitutedand substituted alkyl, phenalkyl and phenyl groups in which substituentsare restricted to members of the group consisting of hydroxy, alkyl andalkoxy radicals on the phenyl radicals, the substituted group on onenitrogen being the same as that on the other nitrogen.

6. The method of preserving rubber which comprises incorporating thereinan N,N' di-substituted 1:5-naphthalene diamine in which each a z-N Nsubstituted group is a benzene ring in which substituents are restrictedto members of the group consisting of hydroxy, alkyl and alkoxyradicals.

7. The method of preserving rubber which comprises incorporating thereinan N,N di-substituted 1:5-naphthalene diamine in which each Nsubstituted group is a benzene ring in which substituents are restrictedto members of the group consisting of hydroxy, alkyl and alkoxyradicals, at least one of said benzene rings containing as a substituenta radical selected from the hydroxy, alkyl and alkoxy radicals.

8. Rubber having incorporated therein an N,N' di-substituted1:5-naphthalene diamine in which each N substituted group is a member ofthe group consisting of unsubstituted and substituted alkyl, phenalkyland phenyl groups in which substituents are restricted to members of thegroup consisting of hydroxy, alkyl and alkoxy radicals on the phenylradicals.

9. Rubber having incorporated therein an N, N di-substituted 1:5naphthalene diamine in which each N substituted group is a member of thegroup consisting of unsubstituted and substituted alkyl, phenalkyl andphenyl groups in which substituents are restricted to members of thegroup consisting of hydroxy, alkyl and alkoxy radicals on the phenylradicals, the substituted group on one nitrogen being the same as thaton the other nitrogen.

10. Rubber having incorporated therein an N, N di-substituted1:5-naphthalene diamine in which each N substituted group is a benzenering substituents are restricted to members of the group consisting ofhydroxy,'alkyl and alkoxy radicals.

11. Rubber having incorporated therein an N,N' di-substituted1:5-naphthalene diamine in which each N substituted group is a benzene.ring in which substituents are restricted to members of the groupconsisting of hydroxy, alkyl and alkoxy radicals, at least one of saidbenzene rings containing as a substituent a radical selected from thehydroxy, alkyl and alkoxy radicals.

12. Rubber having incorporated therein a 1:5- naphthalene diamine inwhich each amino nitrogen carries one hydrogen atom and one hydrocar--bon radical of the group consisting of alkyl, phenalkyl and phenylradicals.

13. The method of preserving rubber which comprisesincorporating'therein a 1:5-naphthalene diamine in which each aminonitrogen car ries one hydrogen atom and one alkyl radical.

14. The method of preserving rubber which 17. Rubber having incorporatedtherein 1:5-

dibutyl naphthalene diamine.

18. Rubber having incorporated therein 1:5- di-p(OH) -phenyl naphthalenediamine.

IRA WILLIAMS. ARTHUR M. NEAL. -'WILLIAM A. DOUGLASS.

CERTIFICATE OF CORRECTION.

Patent No. 2,077,502. April 20, 1957.

IRA WILLIAMS, ET At.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 49, in the table, following "Sulfur" in column D,insert the figure 3; and page 4, first column, line 35, before"substituents" insert the words in which; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 29th day of June, A. D. 1957,

Henry Van. Arsdale (Seal) Acting Commissioner of Patents.

